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Old 12-02-2011, 12:15 PM   #1
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Low Oil Pressure light: Definately not Sludge!

So I pulled the viggen's engine out and replaced every gasket in it including head gasket, resealed the timing cover, replaced the balance and timing changes/pulleys, and oil pump. I cleaned everthing.

The pump clearance was slightly out of spec. I did not replace the timing cover but did replace the pump (big mistake.. maybe) I also did not note the positions of the marks on the oil pump.. (another mistake)

I got her all back together after many months of setbacks, etc,etc.

cranked her up with the return tube off of the turbo, plugs and fuel pump fuse out. No oil pressure, no oil from bottom of turbo.

I pulled the filter off and re-clocked the oil pump several times until oil came out of the filter housing. Reinstalled the now slightly crushed but still unused oil filter and ran her for the first time since august. The lifters filled up, and she ran great for a couple of short test drives.

So now the bad part. I drove her to work, about 30 miles, and when I came to a stop after the highway run, I got a flicker from the low oil pressure light at idle. I stopped and shut her down. In the process of pulling over, I noticed that the light goes out completely when the engine is above idle. Wiggled the wire, checked the oil, and started her back up. She sounded fine, no light, so I went another couple of blocks. light then came back on solid. Still sounded fine.

I shut her down and got her towed home. I have never seen that oil pressure light come on in anger. What do you think?

Has anyone measured the clearance of an oil pump that definately did not work? Anyone run one that was slightly out of spec and had decent oil pressure? There was no scoring on the cover or old pump; I really dont want to pull out the engine to do a timing cover.

Dented oil filter bringing the pressure down at idle?

First case of loctite 518 clogging a pickup?

Main oil tube popped loose in the pan? (The one from the filter side to the firewall side)

Oil thermostat doesnt like brake cleaner?

Oil pump off a tooth? Looks like the inner gear turns faster than the outer, so alignment does not seem like a true problem, but I guess it is??

I'm frustrated. Any help or even commiseration would be fine. This car.....
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Old 12-02-2011, 01:08 PM   #2
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Did you take the oil pressure regulating valve out the bottom of the timing cover to clean it while you had it apart? They can get little bits of junk in them that keep them part way open at idle.

I've seen very worn looking pumps and scored timing covers make sufficient pressure.

Did you prime the oil pump or cooler feed side with oil or assembly lube when you put it all back together dry? If you didn't prime the pump before cranking it over it's possible the main / rod / cam bearings got scored up from being started dry and it's just not holding pressure.

I've also seen an oil pressure sensor that was enough out of spec that it made the lamp come on at idle even though the pressure was fine - it might be a good idea to replace it before you tear anything apart just to see if that's the problem, they are cheap.
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Old 12-02-2011, 01:35 PM   #3
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These are my personal thoughts about T7 Engines. In order to reduce drag @ idle & while cruising with No load, saab in the quest for improving fuel efficency Reduced the Oil pump capacity in 98+ T5 &T7 engines to a Much smaller "barely adequate" Low friction Low drag design. Due to this with engine wear & Excessive bearing clearances we get Lots of flickering Oil lights @ idle.

My solution for high mile "Loose" T7 motors has been to Shim the oil pressure reliefe valve so that maximum pump capacity can fill in those excessive clearances the way the old "More robust" pre 1997 oil pumps did. I use regular hardware store washers, 3-4 usualy under the spring of the cap for the oil pressure relief valve. You can watch the pressure rise on a gauge with each washer you add. My 2c
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Old 12-02-2011, 02:06 PM   #4
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What weight oil is in there?
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Old 12-02-2011, 02:27 PM   #5
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I replaced the pressure valve and spring as well as the oil pressure sender.. hoping its just the sender... I can put the original one back but plan to get some real readings first.

I didn't prime the pump. But I never ran it dry because I didn't want to spin the turbo without oil. I did end up doing quite a bit of cranking with plugs out and fuel pump off trying to get oil to pump though.

As long as I don't have to pull it to do that timing cover, im happy. Even if I have to do main and rod bearings....

Plan now is to check the pressure and shim the valve if necessary. Oil light is only at idle... Will that help on the low side too?

Thanks for the ideas guys. I have some hope now at least.

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Old 12-02-2011, 02:30 PM   #6
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What weight oil is in there?
Good old shell rotella t6 5w 40. Have been running it for at least 40k miles with no issues.
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Old 12-02-2011, 03:15 PM   #7
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Get a guage on there and see what the pressure actually is and go from there. One of the first things to gall up from cranking the engine without the pump primed is the pump housing itself - might be a good idea to pull the crank pulley and pump cover off and see if the surfaces that the pump gears ride on are still nice and smooth. If that's fine then I'd say everything else would be fine too.

I've galled up an oil pump housing from not priming the pump enough before a dry start - not fun. I go crazy now to make sure something like that doesn't happen. I like to pack the pump housing and gears with a little assembly grease, I have a tube of old black-moly assembly lube that works great for this.

If the pump gears just have air in them it generates almost no suction to draw oil up the pickup tube. With the grease / assembly lube it makes a LOT of suction to draw oil up the pickup tube.

Just change the oil and filter pretty quick after getting it running and leak checked.



C900, but same idea:





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Old 12-02-2011, 04:29 PM   #8
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Hmmm pretty sure the pump was dry....

I'll put a gauge on it tomorrow; I hope its just the sender. Pump housing is not so easy on a 9-3. This doesn't look good though.

Maybe I can shim it to compensate and install a permanent oil gauge for now if its not too bad?
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Old 12-02-2011, 05:45 PM   #9
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This stuff works well: AMSOIL - Engine Assembly Lube - EAL (if you order you can use reference #305563, friend of mine)

I just went through a similar situation, same symptoms, but eventually pulled the engine, took the crank back to the machine shop, and found that they polished a little too heavily on the crank journals. The plastigauge had shown top of tolerance so I was suspicious while assembling the thing for the first time...stopping right then would have saved some heartache.

Then when I reassembled the 2nd time, I used an entirely new housing, pump gears, and cover. Wasn't interested in pulling it a 3rd time. Nothing like doing things right the 2nd time. Ugh.
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Old 12-03-2011, 06:33 PM   #10
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No go getting a reading today. Can hook up the gauge or the starter, but both won't fit.


Might try roll starting tomorrw just to get some readings.

Hoping I'm not pulling this thing again....

Thanks for the amsoil number, I'll try that if I need it.
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Old 12-04-2011, 02:07 PM   #11
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well, changed the oil and roll started it. I'm at right around 2 bar at 2krpm.

Spec says 2.5 bar at 2krpm with 10w30. I ran rotella 5w40 because that's what I've been running and I didnt want to change too many variables. would a 10w30 give me that extra half bar I'm missing (half joking here.. But half not joking.

Right around 16 psi (1.1bar) at idle.

It's been idling in the garage for at least half an hour. But it's been dropping the whole time. I used the tap for the oil pressure sender so I know I'm reading what the sender did.

I'll do a quick search for oil psi from other rotella users, but this is not looking good.
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Old 12-04-2011, 03:10 PM   #12
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Neither of those pressures are low enough to trigger the dash light tho as far as I know.



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Old 12-04-2011, 03:32 PM   #13
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Oil light is supposed to trigger @8psi & Below.
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Old 12-04-2011, 04:10 PM   #14
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I know. I wonder if a highway drive could reduce the idle pressure by 50%?? Thats when I got the pressure light. This was all done by idling the car in the garage.

The only other thing that may have affected the outcome was change the oil and filter with more rotella T6 5w40.

My current plan is to install the gauge so I can use the starter again (found an angled fitting that should work) and shim the relief valve until I get my 2.5 bar at 2000 rpm.

Planning to make a more permanent install of the oil gauge with a filter sandwich and go back to using the old oil sender. I simply replaced it as a matter of precaution and to keep everything from leaking.

If I can shim it up to the correct pressure at 2krpm, I'm going to start driving it again.
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Old 12-04-2011, 04:11 PM   #15
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Yup. 16psi at idle (if that's fully warmed up) is fine, make sure the wires in the connector are clean and not corroded, if they are replace the pressure sender.
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Old 12-04-2011, 04:18 PM   #16
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That's excellent news! I'm sure it was fully warmed up. I had it idling for nearly an hour in the garage. No actual driving though, if that matters. I just went around the block after we roll started it.

I think I'll still shim the pressure relief for good measure.

And I'll probably toss out this sender.
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Old 12-05-2011, 09:25 AM   #17
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Yup. 16psi at idle (if that's fully warmed up) is fine, make sure the wires in the connector are clean and not corroded, if they are replace the pressure sender.

I felt the oil cooler and it was scalding. That thermostat only opens above 100C AFAIK?
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Old 12-05-2011, 09:27 AM   #18
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Something like that, might be 90C.
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Old 07-07-2013, 04:59 PM   #19
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Thread still alive?

Would be curious what you ended up doing...

Does the pressure relief valve begin to open before The spec given in WIS? If so then the shimming would make sense, to raise pressure on the piston/valve at all rpms, resulting in higher oil pressure at all rpm when it begins to open.
If not then shimming it only raises pressure at the oil pressure that is stated in WIS. Just curious because I too am having a similar issue. Built b234/235... Checked 3 oil pumps end float. Pulled the sump to check pickup tube o-rings and crossover tube o-rings. Pasti-gauged all the main and rod bearings, again..
Checked to see if the pressure relife valve was stuck, wasn't, it fell right out of the front/timing cover. I even miced 3 springs and 2 pistons to see difference in length and diameters, to no avail.

Curious, are there any oil restrictors in the cylinder head that could have been left out while getting machine work done?

Oil used I treid: m1 10w40: 8 [email protected] idle, [email protected] rpm.
valvoline 10w40 maxlife: [email protected] idle, [email protected] 2k rpm.
Fully warmed up, driving about 30 minutes. Outside air temps are around 90 degrees here, right now. I have even seen 7 psi @ idle after about an hour long drive. I have used 2 mechanical oil pressure gauges and have a dedicated autometer in the car right now.
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Old 07-07-2013, 06:05 PM   #20
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Can you shim the pressure relief valve on the car without pulling covers and engines? I have a car that is showing low oil pressure at idle.

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Originally Posted by Harvey's Autohaus View Post
These are my personal thoughts about T7 Engines. In order to reduce drag @ idle & while cruising with No load, saab in the quest for improving fuel efficency Reduced the Oil pump capacity in 98+ T5 &T7 engines to a Much smaller "barely adequate" Low friction Low drag design. Due to this with engine wear & Excessive bearing clearances we get Lots of flickering Oil lights @ idle.

My solution for high mile "Loose" T7 motors has been to Shim the oil pressure reliefe valve so that maximum pump capacity can fill in those excessive clearances the way the old "More robust" pre 1997 oil pumps did. I use regular hardware store washers, 3-4 usualy under the spring of the cap for the oil pressure relief valve. You can watch the pressure rise on a gauge with each washer you add. My 2c
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